Introduction: Pumpkin is a good source of carotene, water-soluble vitamins and amino acids.Pumpkin can be processed into flour which has a longer shelf-life. Pumpkin flour is used because of its highly-desirable flavour, sweetness and deep yellow orange –red colour. In this study, kinetic modeling of pumpkin drying in an infrared-hot air dryer was investigated.Materials and Methods: The effect of radiation lamp power at three levels of 204, 238 and 272W, hot air temperature at three levels of 55, 65 and 75oC and samples thickness at two levels of 0.5 and 0.7 cm on time and drying kinetics and moisture diffusion coefficient during drying of pumpkin in a completely randomized design were evaluated.Results: The effect of radiation power and hot air temperature on the drying process of pumpkin is significant. Increase in infrared lamp power from 204 to 272 W and increase in hot air temperature from 55 to 75oC reduced pumpkin drying time 15.05 and 37.43%, respectively. Effective diffusivity coefficient of pumpkin moisture was between 9.2×10-10 to 3.3×10-9 m2/s.Conclusion: 272 W power, 75oC temperature and 0.5 cm thickness were the best condition for drying of pumpkin. The effects of infrared heat power and hot air temperature on effective diffusivity coefficient changes were investigated and it was found that the effective diffusivity coefficient increased by increasing heat source power and air temperature. In modeling of pumpkin drying process, Newton model is a better match with the experimental results as compared to other models.

Introduction: Investigation of the mass transfer kinetics and moisture diffusivity coefficients can be useful tools for optimal control of the drying process condition and increasing the product quality.Materials and Methods: In this study, kinetic modeling of persimmon drying in a combined hot air- infrared dryer was investigated. The effect of hot air temperature at three levels of 55, 65 and 75 °C and radiation lamp power at three levels of 150, 250 and 375 W on time and drying rate, and moisture diffusion coefficients during drying process of persimmon were evaluated.Results: By increasing the temperature of drying from 55 to 75oC, 36 % of the drying time was reduced and by increasing the power of infrared lamp from 150 to 375 W the time of drying of persimmon was reduced by 68.4%. The effect of infrared heat power and hot air temperature on effective diffusivity coefficient of persimmon was investigated and the results showed that the effective diffusivity coefficient was increased by increasing the heat source power. Effective diffusivity coefficient of persimmon moisture was between 1.8´10-9 to 1.3´10-8 m2/s.Conclusion: The results indicated that the effect of hot air temperature and radiation lamp power on the drying process of persimmon is significant. In modeling of persimmon drying process, the logarithmic model is a better match with the experimental results as compared to the other models.

Compared to most vegetables, mushrooms have a short shelf life after harvesting due to their metabolic activities and highwater content. This characteristic makes it susceptible to microbial spoilage and enzymatic browning. Therefore, it is very important to choose a suitable maintenance method. In this research, combined osmosis-hot air drying method was used, and button mushrooms were cut in three levels of 3, 5, and 7 mm, and three levels of salt osmotic solution concentration of 10, 20, and 30%, and three levels of retention time in osmotic solution one, they were dried for 2 and 3 h, in a laboratory hot air dryer at a temperature of 60 ̊C and the samples were evaluated in terms of moisture and water reabsorption and sensory evaluation. The results showed that the best cut thickness for drying mushrooms is 5 mm, and the samples that were in the osmotic solution with a lower concentration had a higher water absorption than the rest of the samples, and the evaluation results also showed that the dried mushrooms with a thickness 5 mm, which is 3 h in 20% osmotic solution, has higher sensory characteristics in terms of taste, taste, aroma, smell, appearance color, firmness of texture and overall acceptance.